Vegetable glycerin (VG) is a clear liquid typically made from soybean, coconut, or palm oils—and MONQ diffusers happen to contain an 80% coconut-oil derived vegetable glycerin base.1,2 MONQ is committed to not only offering products designed to promote overall health and well-being but also to educating individuals about what those products are, as we have done in our essential oil library.
Highlighted below is an overview of the properties and safety of VG, specifically when used aromatically.
What Is Vegetable Glycerin?
VG is an organic compound with multiple hydroxyl groups that allow for its solubility in water. It is a colorless, odorless, viscous non-toxic liquid that typically has a sweet taste.3
Because of its properties, VG has multi-faceted uses in a range of industries, from food to personal care. In foods and beverages, VG is used as a sweetener. In medicine and personal care, it can be found in products ranging from prescription or over-the-counter medications to toothpaste.
The metabolism of VG involves its conversion to glyceraldehyde 3-phosphatase before it begins glycolysis. The enzyme that breaks it down—glycerol kinase—is found primarily in the liver and kidneys but also in the muscles and the brain.4,5
When ingested, VG has been found to have very low toxicity, with a lethal dose 50 value (LD50) of 12600 mg/kg in rats and 8700 mg/kg in mice.6
Safety of Vegetable Glycerin in Aromatic Uses
Although VG is recognized as safe by the FDA as a food ingredient, most questions currently center on the safety of blending VG with aromatic compounds for use in aromatherapy.
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According to a range of studies, VG does not negatively affect pulmonary health when used in the absence of other chemicals that are known to be harmful. These include known toxic substances, like nicotine and propylene glycol (PG).
Though PG has the lowest toxicity among glycols and has not been found to be harmful on its own, it forms acetals that can be harmful to pulmonary health when combined with the synthetic aldehydes found in the e-liquids for e-cigarettes.7
A 2017 peer-reviewed study from the Journal of Alternative and Complementary Medicine demonstrated the dangers of PG, especially when heated. In this study, researchers assessed the degradation of PG, polyethylene glycol (PEG), VG, and medium-chain triglycerides when heated to 230°C, a high temperature consistent with some vaporizers. They found that PEG produced acetaldehyde and formaldehyde, two known carcinogens, while PG decomposed into formaldehyde at this temperature.
Notably, VG did not produce detectable amounts of any of these toxins.8
The current human threshold limit value for VG is 10 mg/m3. This value describes the concentration of the substance in the air and indicates the degree to which individuals can be exposed to a substance without adverse effects.
In a 2017 study published in the American Journal of Physiology, researchers used a nebulizer to aerosolize saline or a VG/PG mixture with either 0 or 18 mg of nicotine to 12-week old mice for five days a week for four months.9
Though the study used compressed air rather than a heating source to aerosolize the solutions, they discovered significant differences between the groups. VG/PG/nicotine but not VG/PG increased airway resistance, lung inflammatory cytokines, and apoptosis of alveolar and airway cells—symptoms associated with induced chronic obtrusive pulmonary disease (COPD).
These results highlight the detriments of nicotine inhalation in a VG/PG vessel but do not demonstrate any negative effects of VG use.
Another 2017 study found that PG alone, VG alone, or a VG/PG combination did not significantly affect phagocytosis, which is typically reduced in individuals with alveolar damage and was negatively affected in cells treated with nicotine or e-cigarette solution.10
Finally, a third study published in Food and Chemical Toxicology in 2017 concluded that VG/PG mixtures without nicotine demonstrated no significant biological effects and no signs of toxicity. The addition of nicotine to this mixture resulted in results consistent with known pulmonary side-effects of nicotine exposure demonstrated in previous studies.11
This same study exposed rats to 0.03, 0.16, and 0.66 mg/L doses of glycerin over 90 days and found no treatment-related toxicity at low doses.
All recent studies report that VG is non-toxic when used in proper doses and has only been associated with negative side-effects when coupled with known toxic substances like nicotine, tobacco, or vitamin E acetate.
MONQ diffusers contain only pharmaceutical-grade organic vegetable glycerin and pure, organic essential oils. The diffusers are also designed to maintain low temperatures in order to preserve the healing properties of the essential oils and produce minimal vapor.
Most importantly, MONQ should be breathed gently into the mouth and out the nose where it interacts with the mucous membranes and the olfactory bulb to provide health benefits. MONQ should not be inhaled into the lungs. So, enjoy breathing therapeutic air designed to enhance your health while the science speaks for the ingredients.
Photo credits: HeatherMClark/shutterstock.com, ChoknitiKhongchum/shutterstock.com, PowerUp/shutterstock.com